The present disclosure relates to transcatheter heart valve systems. More particularly, it relates to devices and methods for preparing a transcatheter heart valve system for implanting a stented prosthetic heart valve.
Heart valves, such as the mitral, tricuspid, aortic, and pulmonary valves, are sometimes damaged by disease or by aging, resulting in problems with the proper functioning of the valve. Heart valve problems generally take one of two forms: stenosis in which a valve does not open completely or the opening is too small, resulting in restricted blood flow; or insufficiency in which blood leaks backward across a valve when it should be closed.
Heart valve replacement has become a routine surgical procedure for patients suffering from valve regurgitation or stenotic calcification of the leaflets. Conventionally, the vast majority of valve replacements entail full stenotomy and placing the patient on cardiopulmonary bypass. Traditional open surgery inflicts significant patient trauma and discomfort, requires extensive recuperation times, and may result in life-threatening complications.
To address these concerns, within the last decade, efforts have been made to perform cardiac valve replacements using minimally-invasive techniques. In these methods, laparoscopic instruments are employed to make small openings through the patient's ribs to provide access to the heart. While considerable effort has been devoted to such techniques, widespread acceptance has been limited by the clinician's ability to access only certain regions of the heart using laparoscopic instruments.
Still other efforts have been focused upon percutaneous transcatheter (or transluminal) delivery of replacement cardiac valves to solve the problems presented by traditional open surgery and minimally-invasive surgical methods. In such methods, a prosthetic heart valve is compacted for delivery in a catheter and then advanced, for example through an opening in the femoral artery and through the descending aorta to the heart, where the prosthetic heart valve is then deployed in the valve annulus (e.g., the aortic valve annulus).
Various types and configurations of prosthetic heart valves are used in transcatheter valve procedures to replace defective natural human heart valves. The actual shape and configuration of any particular prosthetic heart valve is dependent to some extent upon the valve being replaced (i.e., mitral valve, tricuspid valve, aortic valve, or pulmonary valve). In general, prosthetic heart valve designs attempt to replicate the function of the valve being replaced and thus will include valve leaflet-like structures used with either bioprostheses or mechanical heart valve prostheses. If bioprostheses are selected, the replacement valves may include a valved vein segment or pericardial manufactured tissue valve that is mounted in some manner within an expandable stent frame to make a valved stent (or stented prosthetic heart valve). In order to prepare such a valve for transcatheter implantation, one type of valved stent can be initially provided in an expanded or uncrimped condition, then crimped or compressed around a balloon portion of a catheter until it is close to the diameter of the catheter. In other transcatheter implantation systems, the stent frame of the valved stent can be made of a self-expanding material. With these systems, the valved stent is crimped down to a desired size and held in that compressed state with a sheath, for example. Retracting the sheath from this valved stent allows the stent to expand to a larger diameter, such as when the valved stent is in a desired position within a patient. With either of these types of percutaneous stent delivery systems, conventional sewing of the prosthetic heart valve to the patient's native tissue is typically not necessary.
The transcatheter delivery system (e.g., the delivery device catheter loaded with a stented prosthetic heart valve) must be free of air bubbles to prevent formation of air embolisms during the implantation procedure. Conventionally, air bubbles are removed by repeatedly flushing the system with a liquid (e.g., saline) to remove air from the system just prior to the implantation procedure. Traditional flushing relies on pushing liquid through the lumen(s) of the delivery device catheter to move bubbles out of the system. This can be difficult with the exceedingly small lumens associated with transcatheter delivery systems, and as the stented prosthetic heart valve is loaded into the catheter, new bubbles can be introduced that are difficult to remove without further flushing.
In light of the above, a need exists for improved devices and methods for preparing transcatheter heart valve systems, including removal of air bubbles.